1. Field of the Invention
The present application relates generally to electronic circuits and more particularly, the present application relates to techniques for providing both short-term and long-term adjustments to the operating frequency of a clock circuit used to clock an electronic circuit device such as an integrated circuit device.
2. Description of the Related Art
Given a system that uses a clock signal for timing (as a digital circuit, for example), an ability to adjust that clock signals' frequency is desirable in order to compensate for various effects (for example, voltage and temperature variations, or aging) or to optimize some measure of performance (for example, maximize frequency of operation, minimize power of operation). The environment influences what frequencies are acceptable to the circuit both in the short term (few clock cycles, few tens of clock cycles) and in the long term (hundreds/thousands of clock cycles). For example, noise in the power supply of a CMOS digital circuit will have a short term effect, while temperature variations of the same circuit will have a long term effect.
It would thus be desirable to provide a clocking mechanism that is suitable for accommodating a widely diverse operation environment with its associated unique clocking requirements.